#pragma warning(disable:4996)
#include<stdio.h>
int main()
{
	unsigned int n;
	double sum;
	sum = 0.0;
	scanf("%d", &n);
	for (size_t i = 1; i <= n; i++) {
		sum += 1.0 / i;
	}
	printf("%.2f", sum);
	return 0;
}